A smart way to make community screening for atrial fibrillation feasible?

8th November 2012

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Jerrett Lau, Concord Hospital, Sydney, Australia, and others reported, at the American Heart Association (AHA) scientific sessions, that a smartphone app could be used to diagnose atrial fibrillation in a community setting.

Lau et al wrote, in their AHA abstract, that a significant proportion of ischaemic strokes are the result of undiagnosed atrial fibrillation and, as atrial fibrillation is often asymptomatic, community screening may be necessary to identify atrial fibrillation patients before they have a stroke. However, they added that, until now. ECG screening “has not been considered feasible”.

In Lau et al‘s study, the AliveCor ECG iPhone app (AliveCor) was used to record a single-lead ECG in 109 patients who had been identified as being in sinus rhythm (70) or as having atrial fibrillation (39) after undergoing a 12-lead ECG. Lau told Cardiac Rhythm News that the app, to work, needs an iPhone case that has recoding electrodes on its back. He explained: “The case is hand held with fingers on either electrode. The ECG is recorded from the contact between the electrodes and the fingers.”

The single-lead ECGs were then uploaded onto the AliveCor server and were interpreted by two cardiologists, who were blinded to the results of the 12-lead ECGs. Also, the server was used to provide an automated diagnosis of sinus rhythm or atrial fibrillation and a third cardiologist compared the results of the single-lead ECG diagnoses with the 12-lead ECG diagnoses.

Lau et al reported: “Sensitivity and specificity of the iPhone single-lead ECG for atrial fibrillation diagnosis, overall accuracy and kappa (ќ) were 100%, 90%, 94%, ќ0.87 for cardiologist A; 95%, 94%, 95%, ќ0.88 for cardiologist B, and 87%, 97%, 94%, ќ0.86 for the automated algorithm respectively.” They added that after algorithm optimisation was performed to enhance sensitivity, the results for the automated diagnosis were 100%, 96%, 97%, ќ0.94, respectively.

The investigators concluded by saying that the AliveCor ECG app was an “ideal enabling technology for community screening programmes to detect silent atrial fibrillation.” They added: “Screening programmes utilising this device could have a substantial impact on reducing ischaemic stroke related to previously undiagnosed atrial fibrillation.”

Lau said that a community screening programme would be directed at people over the age of 65. He added that the device was “very easy to use” and, thus, could potentially be used by patients themselves (to make a recording and then send the results to their doctor for interpretation). About the limitations of the device, Laud said: “Someone who has paroxysmal atrial fibrillation who is in sinus rhythm at the time of the 30-second recording may be missed, but other studies have shown that repeat ECG recordings over time increases the detection rate.”